A network service provider may wish to have accurate knowledge of the locations of its customers. For example, a customer may interact with the service provider via a base station that customer's endpoint device is using to obtain a service. Since the wireless coverage in the vicinity of the customer depends on the proximity of the customer's endpoint device to the cell tower, a geo-fence may be defined for an area considered to be inside the coverage area of the cell tower. Unfortunately, using the coverage area associated with the cell tower to define a geo-fence does not produce accurate results.